Diamond is a mineral composed of pure carbon. It is the hardest naturally occurring substance and popular gemstone. Because of extreme hardness, diamonds have a number of important industrial application. Diamond is a special form of Carbon like Graphite. In the mine, a raw diamond looks like a piece of coal—natural stone. Jewellery grade diamond cutting is a separate and special branch involves marking, cleaving, kerfing, blocking, sawing, bruiting, faceting and polishing.
Inside the raw stone there can be some impurities. The impurities inside the diamond are called NATS and GERUMS. Nats are impurities in the form of particles other then carbon and Gerums are the impurities in the form of micro-cracks in the stone. So, these impurities have to be removed from the stone, and that is why the raw stone is cut in such a way, that the maximum carat weight (volume) can be gained.
Before cutting the raw stone it is planned in the mind by imagination from where to cut to yield the desired value and size. Marking is done on the stone for cutting accordingly. To make this decision, the shape of rough diamond and the number and location of impurities is required to be considered as it affects reflectivity and clarity of the diamond. But the human imagination of the mankind can not judge the proper place of the impurities and it may have error and cutting is done randomly, so there may be lots of wastage. While cutting the stone there are permutation and combination in the form of size and numbers from one stone. When the cutting is done according to the human imagination, the desired proportion of and numbers can not be obtained and there may be a heavy loss.
Gemstone is used as ornamental objects, so, it is valued by their appearance rather than for industrial use. Particularly Gemstone value is calculated base up on the clarity, color, cut and carat. Color generally refers to the diamonds hue, and is related to impurities in the diamond's composition.
Clarity generally refers to defects, such as bulk or surface defects, which can scatter light and reduce a diamond's visual appeal. The cut generally refers to both the diamond's shape (e.g., round, marquise, oval, etc.), and also to the diamond's proportions, symmetry, and polish. These parameters influence how light interacts with the diamond, which facets appear bright to an observer, which facets appear dark, and which facets appear colored.
The impurities inside the diamond are called NATS and GERUMS. Nats are impurities in the form of particles other then carbon and Gerums are the impurities in the form of micro-cracks in the stone. So, these impurities have to be removed from the stone, and that is why the raw stone is cut in such a way that the maximum carat weight (volume) can be gained.
In general practice, gemstone is evaluated by naked eye and optical magnifying glass by experienced skilled persons. They do their experienced efforts to identify internal defects and inclusions. By conventional method they always take care of planning as per their individual decision.
Optionally, gemstone are also evaluated by microscopic systems by experts and it was become little more accurate decision but still completely dependent on visual accuracy and manual inconsistency. However, diamond (gemstone) has very high refraction index and it creates lot of refractions and some total internal reflections due to light angle and uneven shape of rough stone. These all are limitations of the jewelry industry to detect real and precise size and position of inclusions (information) to create better planning and get maximum gain.
U.S. Pat. No. 4,259,011 describes how to identify the presence of inclusions but not their location. European patent 1,211,503, presents a possible solution for the locating of inclusions in a transparent and at least partially polished diamond by imaging the diamond twice and analyzing the images by computer so as to localize an inclusion with respect to the outer surface of the diamond. Although this patent makes reference to a refractive index correction factor to be included in the computer's calculations, it does not provide a solution to multiple images produced by a single inclusion.
U.S. Pat. No. 4,049,350 teaches eliminating the refractions and reflections at the facets of a cut stone by submerging the stone in a solution of similar refraction index. It describes how to locate an inclusion in a two dimensional plane by aiming a narrow laser beam at a preferred angle to a particular facet.
U.S. Pat. No. 4,152,069 also teaches submerging a cut stone in such a solution and how to find the inclusion within a three dimensional volume.
Both latter references do not disclose any information on the medium they used to closely match the refraction index of the gem, this being particularly problematic for diamonds that have a very high refraction index. In some conventional gemstone evolution method hazardous chemicals are used as medium, but during the diamond evolution or scanning method toxic gas in generated. To overcome above stated limitation and to evaluate gemstone more prosaically at microscopic level, the present invention method and device is used.